00538 – Reference Voltage : Signal too small

Possible Causes

  • Common Causes
    • Fuse(s) faulty
    • Wiring and/or Connector(s) from/to Control Module faulty
    • Control Module faulty
  • Heating/Climate Control specific Causes
    • Fuse(s) faulty
    • Wiring and/or Connector(s) from/to Control Module for Heating/Climate Control (J255/J301) faulty
    • Flap Motor/Position Sensor faulty
    • Control Module for Heating/Climate Control (J255/J301) faulty

Possible Solutions

  • Common Solutions
    • Check/Replace Fuse(s)
    • Check/Repair Wiring and/or Connector(s) from/to Control Module
    • Check/Replace Control Module
  • Heating/Climate Control specific Solutions
    • Check/Replace Fuse(s)
    • Check/Repair Wiring and/or Connector(s) from/to Control Module for Heating/Climate Control (J255/J301)
    • Check/Replace Flap Motor/Position Sensor
      • Perform Output Test
    • Control Module for Heating/Climate Control (J255/J301)

Special Notes

  • When found in Control Module for Heating/Climate Control (J255/J301):
    • Disconnect the electrical Connectors to the Position Sensors one after another, erase Fault Codes and check Fault Codes again. If the « Reference Voltage » Fault Code is no longer recognized (and the Fault Code for the reappears after reconnecting), the applicable Flap Motor/Position Sensor must be replaced.
      • When additional components such as G107 (sunlight sensor) are on the same 5V reference voltage supply make sure to unplug all sensors while troubleshooting using this method.

00538 – Reference Voltage : Faulty

Possible Causes

  • Fuse(s) faulty
  • Wiring and/or Connector(s) from/to Battery faulty
  • Control Module faulty

Possible Solutions

  • Check Fuse(s)
  • Check Wiring and/or Connector(s) from/to Battery
  • Check/Replace Control Module

Special Notes

  • When found in Central Electronics Control Module (J519):
    • Specifically check the (Ground) Wiring from the Central Electronics Control Module (J519) to the Battery.
  • When found in the Central Electronics / Body Control Module (BCM) in a (16/AJ) chassis Jetta check fuse SB19.